Vibration suppressor in cathode assembly for electron discharge device

ABSTRACT

An insulator coil vibration suppressor comprised of a resilient member which is electrically insulating is force fitted into the top of a hollow tubular cathode between the interior wall thereof and the outside surface of an insulator which surrounds the heater. The suppressor eliminates vibrations from the coil and thus reduces extraneous noise developed by the tube.

United States Patent 11 1 Hoppel 1 June 19, 1973 1 VIBRATION SUPPRESSOR IN CATHODE ASSEMBLY FOR ELECTRON DISCHARG DEVICE [75] lnventor: Thomas OMarah Hoppel,

Hollidaysburg, Pa.

[73] Assignee: GTE Sylvania Incorporated, Seneca Falls, N.Y.

22 Filed: Sept. 1, 1971 2| Appl.No.: 177,040

FOREIGN PATENTS OR APPLICATlONS 749,312 5/1956 Great Britain 313/340 867,021 5/1961 Great Britain... 313/340 787,458 12/1957 Great Britain 313/340 927,298 5/1963 Great Britain 313/340 Primary Examiner.lohn K. Corbin Attorney-Norman J. OMalley, Donald R. Castle and William H. McNeil! [57] ABSTRACT An insulator coil vibration suppressor comprised of a resilient member which is electrically insulating is force fitted into the top of a hollow tubular cathode between the interior wall thereof and the outside surface of an insulator which surrounds the heater. The suppressor eliminates vibrations from the coil and thus reduces ex traneous noise developed by the tube.

2 Claims, 3 Drawing Figures Patented June 19, 1973 3,740,606

INVENTOR. THOMAS OM. HOPPEL BY I :Dm 2' Q I ATTORNEY VIBRATION SUPPRESSOR IN CATHODE ASSEMBLY FOR ELECTRON DISCHARGE DEVICE BACKGROUND OF THE INVENTION ing such a device is used.

Many types of electron discharge devices are constructed which employ a hollow, tubular, indirectly heated thermionic cathode. These cathodes are raised to their operating temperature by means of a heater which is inside the hollow cathode. In some types of these devices it is desirable to space the heater away from the interior wall of the cathode and this has been accomplished in the past by surrounding the heater with an insulator coil. This insulator is generally made from tungsten wire coated with alumina, as is the heater; however, while one end of the coil, generally the lower end, is connected to one of the stem leads of the device the connection is for mechanical strength only and does not provide any electrical function.

During manufacture of the cathode the heater is first inserted into the insulator coil and then this subassembly is inserted into the cathode. To accomplish this it is necessary that the outside diameter of the coil be slightly less than that of the inside diameter of the cathode. If the fit of the insulator coil is too tight it is apt to damage the insulating coating on the coil, an undesirable condition since this reduces the degree of electrical insulation required. If the coil is too loose, so that insertion is easy, then the coil is liable to vibrate, developing unwanted noise in the circuitry in which the device is utilized.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of this invention to obviate the disadvantages of the prior art.

It is another object of the invention to stop vibration of an insulator coil. I

These objects are accomplished in one aspect of the invention by the provision of a cathode assembly which comprises a hollow body. A heater having an electrically insulating coating thereon is positioned within the cathode body and is surrounded by an insulator coil of generally helical configuration. An insulator coil vibration suppressor is fitted between the insulator coil and the interior wall of the cathode at one end thereof. The vibration suppressor keeps the coil from vibrating and is inserted into the cathode after the coil and heater. This allows thecoil to be made of sufficiently small diameter to allow for easy insertion without acquiring any of the undesirable effects of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of the cathode assembly of the invention;

FIG. 2 is an elevational view of a cathode assembly with parts broken away showing the invention in use; and

FIG. 3 is a plan view of the cathode assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above-described drawings.

Referring now to the drawings with greater particularity, there is shown in FIG. 1 a cathode assembly for use in an electron discharge device. Assembly 10 comprises a hollow, tubular cathode body 12 which can.

be either circular, rectangular or other configuration in cross-section and which has an electron emissive material 14 thereon. The body 12 has an inside diameter A. A heater 16 is formed to be inserted into the body 12 and can comprise a folded segment of resistive wire,

- such as tungsten which has an insulating coating such as alumina thereon. Surrounding the heater 16 is a helical insulator coil 18 which is resilient and which can also be a wire coated with alumina or similar material. The coil 18 has a diameter B which is less than A to achieve easy entry thereinto. The function of the insulator coil 18 is to space the heater 16 away from the interior surface 20 of body 12.

A portion of the lower end 22 of insulator coil 18 has the insulation removed so that it can be mechanically connected to a support.

To prevent the insulator coil from vibrating and setting up unwanted signals in associated circuitry, there is provided an insulator coil vibration suppressor 24 which comprises in this instance a substantially V- shaped member whose legs have a diameter C. The leg diameter C is greater than A-B/2. v

FIGS. 2 and 3 show the placement of the suppressor 24 within the cathode body 12. As can be seen therein, the lower end 22 of coil 18 is welded or otherwise permanently affixed to a support 26, which in this instance can be one of the lead-in pins of the device. This mechanical connection sufficiently prevents vibration of the lower end of the coil 18, and the use of the coil vibration suppressor 24, which is inserted from the opposite end of the cathode, effectively prevents vibrations therefrom.

While not necessary in the performance of its function, the insulator coil vibration suppressor 24 can be more easily inserted if one of the legs is made longer than the other. Also, to prevent undue crushing of the coil 18 and the heater 16 the diameter C of the legs should be less than A/4.

While there have been shown what are at present the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined by the ap pended claims.

What is claimed is:

l. A cathode assembly for an electron discharge device comprising: a hollow tubular body; a heater having an electrically insulating coating thereon positioned within said body; an insulator coil having a generally helical configuration surrounding said heater within said body; and an insulator coil vibration suppressor comprising a separate and distinct member positioned between said coil and the interior wall of said cathode at the upper end thereof, said insulator coil at its lower end being mechanically connected to a support; said low cathode body has an interior diameter A; said insulator coil has an outside diameter 8 which is less than A; and said legs of said resilient member have a diameter C which is greater than A-B/2 and less than A/4.

CERTIFICATE OF CORREQTEON v Patent N5. 3,740,606 Dated June 19, 1973 Inventoflg) ;Thomas O'Marah Hoppel It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 34 "C"is greater than A-Bl/Z" should read "C' is greater than 5 I Col. 4, Claim 2, line 4 "C" is greater than A-B/Z" should read "C" is, greater than A-B Signed and sealed this 237th; day of November 1973..

(SEAL) Attest:

EDWARD I LFLETCHERJR. I RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents 

1. A cathode assembly for an electron discharge device comprising: a hollow tubular body; a heater having an electrically insulating coating thereon positioned within said body; an insulator coil having a generally helical configuration surrounding said heater within said body; and an insulator coil vibration suppressor comprising a separate and distinct member positioned between said coil and the interior wall of said cathode at the upper end thereof, said insulator coil at its lower end being mechanically connected to a support; said insulator coil vibration suppressor comprising a substantially Vshaped, resilient member, the legs of which are inserted between the inner wall of said cathode body and the outer surface of said insulator coil.
 2. The cathode assembly of claim 1 wherein said hollow cathode body has an interior diameter A; said insulator coil has an outside diameter B which is less than A; and said legs of said resilient member have a diameter C which is greater than A-B/2 and less than A/4. 